Turbidites


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Related to Turbidites: turbidity currents

Turbidites

 

deposits from turbidity currents on the floor of the seas and oceans, consisting of clastic sediments of various sizes and different degrees of roundness.

The periodic deposition of sediments from turbidity currents on the sea floor disrupts the usual process of sedimentation and produces a series of cycles in sea-floor sediments; the boundaries of the cycles are usually distinct, and the thicknesses vary (usually a few tenths of a centimeter, less often fractions of a centimeter to several meters). In the lower part of each cycle the most coarsely grained sediments grade upward into more finely grained sediments, resulting in graded bedding. The cycle is completed by a thinner layer of argillaceous or carbonate pelitic sediment.

Different slope steepnesses, transport times, and degrees of turbidity-current loading or liquidity cause differences in the structure of turbidites. The remains of shallow-water and littoral organisms transported by a turbidity current are found in the deep-water sediment. The volcanogenic material tephra is sometimes present in turbidites; such sediments are called tephroturbidites. In mineral form they are known as tuff turbidites. Turbidites are widespread among recent and ancient deposits of various ages, especially among sediments in seismically active areas.

L. N. BOTVINKINA

References in periodicals archive ?
Sparse fossil age control suggests that thin-bedded ("pinstriped"), well-graded silt-mud turbidites of the Waterville Formation are of Llandovery age and therefore at least partially temporally equivalent to the coarser grained, thicker bedded Sangerville Formation (Pankiwskyj et al.
The deltaic sandstone of the Khojak Formation, turbidite succession of the Panjgur Formation and molasse strata of the Muree Formation (Himalayan fore lands) have recorded outstandingly similar detrital modes (Critelli and De Rosa, 1987; Critelli et al.
This clast-dominated horizon conforms to the S1 division of Lowe's (1982) model for high density and coarse-grained turbidites.
In 2007 a project was started to work with DZ in Northern Venezuela, sampling Cretaceous Passive Margin and Tertiary turbidite formations [1, 2].
TAPHONOMY, CRONOSTRATIGRAPHY AND PALEOCEANOGRAPHIC IMPLICATIONS AT TURBIDITE OF EARLY PALEOGENE (VERTIENTES FORMATION), CUBA
Key words: Tsunami, Earthquake, Littoral current, Continental talus, Turbidites, Sea level raise.
2001) reported that the structural complexity increases to the west and down section towards the basal units within the turbidites, where folds become tighter and have shorter wavelengths near the contact with the mafic volcanic rocks.
Sediments in the area were found to include post-Kimmeridgian turbidites.
Zones of constant activity in some of the box cores are attributed to either bioturbation in the surface mixed layer or turbidites.
Marine geologists label such formations turbidites.
Detailed stratigraphic work in the Shimanto belt of Japan, for example, showed an orderly sequence before disruption: oceanic basement (basalts), pelagic sediments, hemipelagic sediments with silicic tephras and muddy turbidites, and coarser grained turbidites, basically similar to that found in the Nankai Trough.
serpentinite bodies within turbidites or ophiolitic wedges against rhyolite flows.